Give the Domestic Shorthair a starter room of its own
A Domestic Shorthair arriving in a home with a resident pet should start in one small room, not with the run of the house. Equip it with litter tray, food and water placed apart from each other, a scratching surface, and both a hiding place and a raised resting spot. A small room is not a punishment; it is how a cat in an overwhelming new territory gets one manageable space where everything smells increasingly like itself. Until the new Domestic Shorthair is eating well, using the tray reliably and coming out to explore its room confidently, it is not ready to process a resident pet on top of a new home, new people and new sounds.
Let scent do the first introductions for both animals
Scent exchange lets a Domestic Shorthair and a resident pet meet in the order cats naturally prioritise. Swap the bedding each animal sleeps on, stroke each one's cheeks with a cloth and leave that cloth near the other's food bowl, and let them investigate under the closed door. Feed both animals their meals on opposite sides of that door, at whatever distance keeps both eating calmly, closing the gap gradually across days. Watch the resident pet as closely as the newcomer: an established animal who stops eating, starts hiding or begins guarding the door is finding the change hard, and slowing down protects the relationship you are trying to build. A Domestic Shorthair from a shelter may carry unknown history with other animals, so unhurried scent work is where you learn what you are working with.
Protect the resident pet's routine while the newcomer settles
A first introduction goes better when the resident pet's life stays recognisably the same. Keep its feeding spots, sleeping places, walk times and one-to-one attention where they have always been, so the resident does not experience the Domestic Shorthair's arrival as a series of losses. If the resident is a dog, practise calm behaviour around the starter-room door and reward ignoring it; if the resident is a cat, make sure it keeps access to its favourite perches and to you. Jealousy is less the issue than resource security: animals accept newcomers far more readily when food, rest and human attention are visibly not in shorter supply than before.
Move to sight, then short shared time, at this cat's pace
Once both animals are relaxed about scent and door feeding, let the Domestic Shorthair and the resident pet see each other through a barrier — a mesh door, stacked gates or a door held slightly open and secured. Short sessions that end on calm behaviour teach more than long ones that end in a squabble. In the first shared-room sessions, give the cat height and exits, keep a resident dog on a lead, feed or play with both at a distance, and separate them again after a few minutes. A Domestic Shorthair's individual temperament drives the timing from here: confident cats may be sharing space within a week, while a timid one may need the barrier stage for several weeks, and both timelines are normal.
Finishing the introduction and settling into one household
A Domestic Shorthair introduction is complete when both animals eat, rest and move around shared space without monitoring each other, and the newcomer uses rooms beyond its starter room confidently. Sharing the stage plan, feeding positions and each animal's progress notes through KinsLe Family Sharing keeps every household member advancing the introduction at the same point, so the cat never gets a rushed meeting from one person and a careful one from another.